Pencil and crayon rod



Patented Nov. 12, 1940 UNITED, {STATES PENGILANDGRAYON ROD i Isidor Chesler, Oceanport, N. J assignor to Eagle" Pencil Company, New York, N.. Y., a corporatio n of Delaware No Drawing. Original application April 14, 1934,

SerialNo. 720,573. Divided and this application December 27, 1937, Serial N04 181,999

5 Claims. (c 106-5) Among the objects of the present invention are to provide a lead rod of the non-calcined type, which admits of being made in any desired length, shape or color, including also black and white and of any desired hardness or softness, which, even in small diameters has tensile and shearing strength, as well as elasticity of high order,v which admits of having incorporated therein waxy or fatty material to determine certain of the writing qualities thereof, the strength and writing qualities of which rod are not ade versely aifected by the glue usedior bonding the same into a conventional wooden case, and which admits of being sharpened" to a point like or-' 15 dinary graphite pencil leads. 1

Another object is to provide a lead or crayon rod composition having the above properties and which is neither too horny nor too tough, but the ingredients of which, including the binder, wear go readily and uniformly with the writing end of the pencil or crayon rod as the latter is consumed in use and which will not powder or harden or otherwise deteriorate withage to such extent as to impair its usefulness. V 25 Another object is to provide a pencil or crayon rod of the above type, in the manufacture of which conventional equipment and processes may be employed. 1 1

According to the present invention the crayon ingredients of pigment and filler may be entirely conventional but a novel binder is used which imparts to the crayon or pencil the properties and characteristics indicated in the foregoing statement of objects and more fully set forth hereinas after.

According to the invention the said binder is an agglutinant which consists of etherized cellulose including a water soluble adhesive mass having distributed therein portions of such sub- 40 stance that are stringy in structure and relatively insoluble in water. With the use of such binder the stringy elements become oriented longitudinally of the crayon or lead rods as these are prepared in the usual manner by extrusion under 45 hydraulic pressure. The resultant lead or crayon rod as a consequence has not only the inherent strength imparted to it by the adhesive character of the agglutinant but the stringy relatively insoluble particles thereof lend further mechanical 50 strength to the lead or crayon to toughen it so that it may actually be dropped on a hard floor without cracking or breaking and may be bent through a very substantial are before it will fracture. Yet the stringy elements are not so tough 55 and horny as to interfere with the writing properties of the lead or crayon but they wear down with the body of the leadas the latter is consumed in writing. f

This application is a'division of my parent application Serial No. 720,573, filed April 14, 1934, 5' and patented on January 11th, 1938, under No. 2,105,310 in which the agglutinant per se is claimed. l l a Forthepresentpurpose it is sufficient to refer briefly to a typical one of the numerous possible ,examples of more or less equivalent agglutinants described in the parentc'ase. i g

The binder which flo'cculent when dry may consist largely of dimethyl ethyl ether of cellulose which ields a gummy-medium when treated 15 with waterinwhich it is soluble. The ingredient set forth has admixed therewith, other ethers of cellulose, poorer orjlacking in the methyl radical and desirably withnot less than two ethyl radicals which ethers are substantially insoluble in water and form the stringyingredient of the binder. Preferably the ingredients'areselected in such proportionsand the process of their preparationis so conducted in accordance with the technique familiar to those skilled the art, that 25- the base mixtureused for the lead or crayon com- 36 position comprises a filler such as-ground china clay and a pigment such as'lilnglish red ground wet, comminuted, filter pressed and air dried, and after admixture with stearic acid and further crushing, is admixed with calcium stearate andstill further mixed. Thereupon the binder in desired proportion of water soaked agglutinant is added, together with enough water to bring the mass to the desired consistency or plasticity. Experience has shown that a preferred moisture 40 content, determinable by analysis of a specimen will range around 20 to 25%.

The mixture of the batch is now ground, com-, pressed and kneaded by use of a series of appropriate mills for securing a homogeneousintimate- -ly mixed and tough dough, which is thereupon hammered into cylinders and forced through perforated plates and re-compressed. Finally the dough is forced under hydraulic pressure through materially augment the mechanical strength of the product.

The lead rods are dried in racks, including covering the leads with rubber mats to prevent Warping thereof, in a conditioned atmosphere Wherein the relativev humidity is automatically main tained around 40, at room temperature. The time of drying or curing varies with the particular kind of lead for periods of from one to eight weeks or until the moisture content is reduced to less than 3% whereupon the leads are cut to specified lengths.

- The rod tightly compacted by the process above set forth develops or has therein minute pores, probably due to the escape therefrom of water evaporated in the drying operation. Except for some types of rods, such as rods made with water soluble dyes, which are used for copying pencils or the like, as well as rods made for special writing characteristics, the rods are subjected to a waxing operation now to be set forth. For such purposes, the dried rods [after reheating to approximately the temperature of the molten wax to be used in the next step are then immersed for a period of some hours in a mixture of waxes, or material of a waxy nature, ordinarily equal parts of stearicacid and carnauba wax, preferably at a temperature of 180 to 190 degrees F. The dried rod has sufficient porosity to permit such melted waxy substances thoroughly to permeate the same, under the conditions of treatment, that is, to substantially fill all voids left in the rods by the evaporation of the water, and to fill the interstices in the stringy ingredient of the binder, apenetration attainable with much difficulty, if atall, where the lead has, a case-hardenedimperforate surface. The thorough Wax impregnation results in a lead or crayon rod of excellent and uniform writing properties. After cooling, the leads, are tested for strength, grade and quality and then preferably glued into the usual wooden sheaths. I

, The lead has tensile and shearing strength considerably greater than that of the best grades of leads of corresponding size at-present on the 'market, and canbe bent through a visible are As many changes and variations may be made in the above article and many apparently widely different embodiments of this invention may be made without departing from the scope of the claims, it is intended that all matter contained in the above description, shall be interpreted as illustrative and not in a limiting sense.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A pencil or crayon rod composed of filler, pigment and binder ingredients, said binder including water solubleetherized cellulose pervading the rod and including also stringy etherized cellulose elements, substantially insoluble in water, wearing flush with the writing end as the rod is consumed in use.

2. A pencil or crayon rod composed of filler, pigment and binder ingredients, said binder including water soluble etherized cellulose pervading the rod and including alsostringy etherized cellulose elements substantially insoluble in water, directed generallylongitudinally of the rod and wearing flush with the Writing end as the rod is consumed in use. r

3. The combination recited in claim 2 in which the stringy etherized cellulose elements of the binder are from 15 to 25 per cent by weight of the binder.

4. A pencil or crayon rod comprising filler, pigment and binder ingredients, said binder including water soluble etherized cellulose dissolved in water and having stringy particles of etherized cellulose distributed therethrough (that are rela-- tively insoluble in water and a waxy substance permeating the rod.

5. A pencil or crayon rod comprising filler, pigment and binder ingredients, said binder including water soluble etherized cellulose as a constituent of the rod and including also small stringy particles of substantially water insoluble etherized cellulose, said particles being directed generally longitudinally of the rod and wearing flush with the writing or wearing end of the rod as the same is consumed in use, and a waxy substance permeating the interstices of the rod proper and also of the stringy particles of the binder thereof.

ISIDOR CHESLER. 

